For example, in a solid-state imaging device which has color filters of primary colors R (red), G (green), and B (blue) and acquires color images, pixels (photodiodes which are photoelectric conversion elements) for red detection, pixels for green detection, and pixels for blue detection are provided on a semiconductor substrate. On the individual pixels, micro lenses (top lens) are stacked, and incident light condensed by the individual micro lenses enters pixels corresponding to the micro lenses, through corresponding color filters.
Recently, with an increase in the number of pixels, solid-state image sensing elements having 10 million pixels or more have become normal. For this reason, each pixel has been miniaturized, and the size of each pixel also has approximated the order of the wavelength of incident light. However, on the optical principles, it is impossible to make the focal point of a lens within a distance equal to or less than the wavelength of incident light. For this reason, it is impossible to condense red light having the longest wavelength among the red light, green light, and blue light within a distance equal to or less than a wavelength of about 700 nm. Therefore, there is a high probability that red light will leak into neighboring pixels, resulting in color mixture or crosstalk.
For this reason, in the related art, as described in Patent Document 1, the light receiving areas of pixels are set to decrease in the order of R pixels, G pixels, and B pixels, such that the areas of the red (R) pixels for receiving light having a long wavelength are large, whereby color mixture or crosstalk is reduced.
Patent Document 1: Japanese Patent Application Publication No. 2010-129548
Like the related technology disclosed in Patent Document 1, if the sizes (light receiving areas) of pixels are set differently according to the wavelengths of incident light components, it is possible to reduce color mixture and crosstalk. However, if the sizes of pixels depend on the colors of incident light components, differences in characteristics such as a characteristic of reading acquired image signals from pixels (photodiodes) (a read voltage), and the saturation characteristic of each pixel arise between the individual colors, and this is a problem.
An object of the present invention relates to a back-illuminated solid-state image sensing element, a method of manufacturing the back-illuminated solid-state image sensing element, and an imaging device capable of reducing crosstalk of pixels receiving long-wavelength light with neighboring pixels, without changing the characteristics of each pixel such as a read characteristic and a saturation characteristic.